Golden Alga Hits Lake Texoma, Remains Active Elsewhere

Steve Lightfoot, 512-389-4701,

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AUSTIN, Texas — Fish kills along the southern shoreline of Lake Texoma are being attributed to golden alga, which is naturally occurring and secretes a fish killing toxin. This dashes the hopes of environmental scientists and fisheries biologists in Oklahoma and Texas that any extensive damage from the lingering presence of the alga on this border lake might be avoided.

The outbreak on Lake Texoma is believed to have begun sometime around March 6, however, large concentrations of affected fish were not observed until later that week. Initial estimates place the loss at upwards of one half million fish based upon Texas Parks and Wildlife Department surveys conducted along the Big Mineral Arm of the reservoir on March 12. Threadfin shad, an abundant forage fish, comprised the majority of the kill, but small numbers of largemouth bass, crappie and bluegill were also affected.

"We’re taking this situation very seriously," said Phil Durocher, TPWD Inland Fisheries Division director. "Texoma is an important lake, not only to us but also to Oklahoma and we’re going to do everything we can to mitigate losses. Right now we’re working jointly with our counterparts in Oklahoma and just trying to get a handle on what’s happening. We’ll continue to monitor the situation and collect the same type of data we’ve been gathering on other lakes where golden alga has occurred."

No other fish kills have been reported elsewhere on Lake Texoma.

TPWD and the Oklahoma Department of Wildlife Conservation have been monitoring the 84,000-acre reservoir for possible spread of golden alga since a fish kill back in January on a 150-acre off-channel lake in upper Lake Texoma was traced to the toxic alga.

"We were hoping the weather would warm up and Texoma would not be affected this year, but it didn’t happen," said Durocher. "This is a natural thing. Why the alga started up now, we have no idea."

While both Texas and Oklahoma are directing resources to Lake Texoma to address the outbreak there, TPWD officials remain concerned about several other golden alga-related incidents elsewhere.

A smaller kill was reported on Possum Kingdom Reservoir northwest of Fort Worth. Staff at Possum Kingdom State Park and also lake rangers are monitoring the area closely since it is the vicinity where two previous major golden alga kills started.

An estimated 10,000 threadfin shad were also killed as a result of golden alga on Lake Granbury. A kill was also reported on Lake Whitney, but an investigation by TPWD staff did not find any unusually high numbers of dead fish.

Another small kill was also reported in Lake Diversion, southwest of Wichita Falls. No estimate of losses has been completed yet on this water body.

In West Texas, several toxic sites are still being monitored by officials, including one in the Pecos River in New Mexico. An extended kill has continued in this area for more than a month. A few dead fish have drifted into Red Bluff reservoir as a result.

Some dead fish were also found on E.V. Spence Reservoir near San Angelo and Lake Colorado City. Water samples from both areas varied between moderately to highly toxic to test organisms, but fish losses have been quite low. And a small but persistent fish kill continues in the Colorado River below Ballinger.

"One encouraging note is that Moss Creek Lake, which experienced a golden alga outbreak, may be recovering," according to Jack Ralph, TPWD Kills and Spills Team leader. "It still contains some golden cells, but tested non-toxic to fish for the first time in more than two years. Prior to this the waterbody had maintained a viable population of P. parvum and continued to kill fish."

First discovered in Texas in 1985, golden alga (Prymnesium parvum) was identified in a fish kill in the Pecos River and has since been responsible for fish kills in the Colorado, Canadian, Wichita and Brazos river systems as well. This is the first reported finding in the Red River basin downstream of Lake Kemp and Diversion Lake on the Wichita River.

Since 2001, golden alga fish kills have occurred on two dozen reservoirs in Texas. Since 1985, nearly 18 million fish have been killed. Although significant numbers of game fish were affected in several areas, most of the fish killed were either forage or rough fish species.

To help keep anglers and other stakeholders informed about golden alga, TPWD has developed a Web site dedicated to harmful algal blooms.

The site ( will be a "clearinghouse" for information about harmful algal blooms, including scientific research updates, details and up-to-date news during an active bloom.